When presidents become comedians-in-chief

Washington will mix with Hollywood Saturday night at the White House Correspondents' dinner, also known as "nerd prom." The event celebrates the accomplishments of the White House press corps, but it also gives the president a chance to roast those reporters.

It's one of the oddities of American politics: a night when the commander-in-chief is required to be a standup comedian, reports CBS News correspondent Margaret Brennan. This will be President Obama's final performance as a sitting president, and he'll try to have the last laugh.

Mr. Obama's jokes have ranged from self-deprecating to partisan.

"These days the House Republicans actually give John Boehner a harder time than they give me. Which means orange really is the new black," Mr. Obama said in 2014, as the room erupted into laughter.

It's a night where the president becomes comedian-in-chief.

"I believe we're an America that should come together, Republican and Democrat and John McCain," President George W. Bush said in 2006.

"Over the last few months, I've lost 10 pounds. Where did they go?" President Bill Clinton said in a suspicious tone in 2000.

The press is a common target.

"MSNBC is here. They're a little overwhelmed. They've never seen an audience this big before," Mr. Obama said in 2014.

Jeff Nussbaum wrote jokes for many of Mr. Obama's Correspondents' Dinner speeches and says humor can defuse the sharpest political fights.

"It's one of the constructive outlets for our political road rage," Nussbaum said.

In 2011, Mr. Obama skewered critics like Donald Trump who raised suspicions about his Kenyan ancestry.

"Tonight for the first time, I am releasing my official birth video," he said, showing an iconic "circle of life" scene from "Lion King."

"Donald Trump is here tonight. No one is prouder to put this birth certificate matter to rest than the Donald. And that's because he can finally get back to focusing on the issues that matter like, 'Did we fake the moon landing?'" Mr. Obama said.

"Do you think the president elevated Donald Trump to his level by spending so much time making fun of him?" Brennan asked Nussbaum.

"Well, humor is such a powerful tool for a lot of reasons, but one is that it is absolutely a dagger that you can stick in your opponents," Nussbaum responded.

The pressure is on the professional comedians to keep up.

"Mr. President, you remember when the country rallied around you in hopes for a better tomorrow? That was hilarious," Jimmy Kimmel said in 2012.

Some say Stephen Colbert's jokes crossed the line.

"Oh, they're just rearranging the deck chairs on the Titanic. ... This [George W. Bush] administration is not sinking. This administration is soaring! If anything, they are rearranging the deck chairs on the Hindenburg!" Colbert said in 2006 to mild laughter.

"Stephen Colbert, I think his goal wasn't to be asked back," Sen. Al Franken said, laughing.

The former comic-turned-senator gave the keynote twice in 1994 and 1996.

"There's a little tricky navigating this because there are some people in Washington who live to be offended," Franken said.

One certainty: Mr. Obama will have fun at the expense of those racing to succeed him.

"I have one friend, just a few weeks ago, she was making millions of dollars a year, and she is now living out of a van in Iowa," he said in 2015.

It does not appear that Democratic presidential candidate Hillary Clinton will attend this year, but rival Bernie Sanders will go as a guest of CBS. As for Republicans, neither Ted Cruz nor Donald Trump will be there -- but it's a pretty safe bet that won't save anyone from some good-natured ribbing.